There is nothing wrong with opening your OnePlus 3T smartphone out of the box and leaving it exactly how it is and using the Android operating system how the Android developers and manufacturers have collectively pieced it together for you to use. In fact, many people take great pride in using the smartphone exactly the way it was made for them even when it makes no sense for them to do so because they are more than happy to sacrifice what would be a more efficient life for themselves just so they can use something the way the brands had designed for them to use it. They do it because it makes them happy to do it.
Then there are the other people: the ones who would much prefer having only the applications that they want to have installed instead of all the apps that the manufacturers and Android wanted them to have; the one’s who want the features of the device that are better suited to them instead of the features and that are made to be a compromise for everyone around the world, the one’s who want customization to make the device better suit their needs.
If you are one of the people who fall into the latter category, then you are going to want to install a custom recovery and get root access on the device. By getting the root access to the Android operating system, you are then opening up the doors for installing more apps—all apps—and apps that otherwise could not have been installed on your device. Additionally, if you are installing a custom recovery, then you are making it possible to have different ROMs installed on your device—custom ROMs that come with various features and design changes than the version of Android that you are seeing running on your device at the moment.
But before you can do any of that on your OnePlus 3T smartphone there is one thing standing in your way, and that is the bootloader. A custom recovery cannot be installed on the OnePlus 3T (Or any other smartphone for that matter) when the bootloader is still locked. The bootloader is what loads before the operating system, and its job is to decide what happens next. It’s a very stubborn feature that will always boot the operating system that it is told to boot (Android) unless we change the way it thinks. That is what we are doing by unlocking the bootloader: we are then telling it how to think differently and making it acceptable in its mind to load something different instead.
Files We Need
1. Download the ADB for Windows operating systems on your computer. (There is also ADB for Linux and ADB for Mac if you use one of those other operating systems, but you need to know the ADB commands for those other operating systems before you can use them because they are not the same as the Windows commands.)
2. Download the Universal Windows ADB Driver on the computer.
Unlocking the bootloader on the OnePlus 3T smartphone
1. Download the ADB on the computer and then right-click on the file and select the “extract” option and extract it to the desktop or Downloads folder.
2. Download and install the Universal Windows ADB Driver on the computer so your ADB can detect your device when you want to connect to it.
3. Go to the “About phone” menu on the phone and tap over the build number at least seven times so you unlock the Developer Options menu on the phone.
4. Go back to the “Settings” menu now and then enter the Developer Options menu and enable the “USB Debugging Mode” option from the menu.
5. Connect the OnePlus 3T smartphone to the computer with its official USB cable.
6. Open the folder where you have the ADB, right-click in the folder where it shows the white background and then choose the “open command window here” from the menu. Doing so launches the command prompt window that you need to run the ADB commands.
7. Type the “adb reboot bootloader” command into the command line and then press the Enter key on the keyboard to get the OnePlus 3t smartphone into its bootloader mode.
8. Type the command “fastboot devices” and check that you can see your device in the list. If your device is not listed, then you still need to get the drivers working which can be done from the Universal Windows ADB Driver package or by finding the official OnePlus USB Drivers and installing them on the computer.
9. Now type the command “fastboot oem unlock, ” and the bootloader on the OnePlus 3T smartphone will then unlock all by itself.
10. Reboot the OnePlus 3T smartphone before doing anything else.
The OnePlus 3T bootloader is now unlocked, and you are ready to find out what is required for getting a custom recovery image installed on the OnePlus 3T smartphone. The custom recovery image is what you need to be able to install custom kernels, custom ROMs and flash the SuperSU.
Once you have a custom recovery installed, you can then find out everything it takes to root the OnePlus 3T smartphone by flashing the SuperSU application from the recovery image. Rooting the device is what makes it possible to install the root applications. These are the apps that cannot run on your device after you install them unless they can get access to the internal system because that is what is required before those apps can work.